Implementation of active control on flexibly mounted pipe exposed to vortex induced vibration using rotating rod

Abstract

This paper presents the experimental works on the active control implementation of a flexibly mounted cylinder exhibiting vortex induced vibration phenomena. The dynamic response of the system was initially studied by fixing single and double passive control rods to the main cylinder. It was found that the fixed control rod could not suppress the vibration for both cases. In fact, the vibration was amplified as compared with the bare cylinder response. By retaining the same position, an active open loop control strategy was introduced to the vibrating system by rotating the single control rod in clockwise and counter clockwise directions. The results indicated that the counter clockwise direction has suppressed the vibration up to 29.81 dB. Further investigation was made by studying the performance of the control rod at several speeds in a single reduced speed of 4.29. It was found that the maximum attenuation level of 19.56 dB was attained based on 1676 RPM of control rod rotating speed. In addition, an overview of attenuation level trends at both varying control speed and reduced speed were presented in this study. Through the experimental implementation of control strategies conducted in this research, it was found that the active control strategy has performed well as suppression strategy at ineffective fixed control rod position.